


Long Live the Kings

by fandomizedpsycho



Category: Sherlock (TV), Supernatural
Genre: Crossover, Demon Sherlock, Demons, Gen, Pre-Apocalypse, Pre-Reichenbach, Supernatural Elements, superlock
Language: English
Status: Completed
Published: 2014-06-14
Updated: 2014-08-10
Packaged: 2018-02-04 13:53:43
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 11
Words: 12,518
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1781458
Author URL: https://archiveofourown.org/users/fandomizedpsycho/pseuds/fandomizedpsycho
Summary: <blockquote class="userstuff">
              <p>Dean and Sam find themselves in London to track down Lilith and try to stop her from breaking the next seal. Meanwhile, strange and unexplained deaths are right up Sherlock's ally. Sherlock and John must work together with team free will when evil forces threaten them all.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> So this is my first time writing a crossover. I don't think there are enough superlock fanfics out there (although the ones I've read were excellent) and this idea would not leave me alone so here it is. Please let me know your thoughts, I thrive off of feedback! 
> 
> I'm sorry for the shortness of this chapter. The next one (which is almost finished) will be a lot longer. 
> 
> Also, I am not British so I'll apologize in advance for any errors. I do watch a lot of Sherlock and Doctor Who but when I'm writing from Sherlock's POV please don't hesitate to correct me!

**Chicago, Illinois**

            Dean Winchester was sitting quietly in yet another shady motel room at a motel that he couldn’t quite remember the name of at the moment. From the outside it would appear that Dean was quite calm. He was sitting on his laptop, a bottle of beer sitting on the table next to him. On the laptop, there was a page open to the _Chicago Tribune’s_ top news stories. He was staring at it but not really seeing it. There wasn’t much to see anyway. There were no major news stories today, no bizarre, strange, or unexplained deaths. Not in Chicago or even the whole state of Illinois. They were only here because they had recently solved a case in a small Indiana town, which turned out to be an angry spirit, not even demonic activity and after that Sam suggested that they head west because why not. The demons were being strangely quiet these days and they knew that Lilith must be planning something big, probably to break another seal. But this knowledge did nothing to help them at the moment.

            However, the frustration that Dean was feeling was not so much due to their lack of leads but more so of the fact that he had called Sam three times and had yet to hear from him. Dean knew, just _knew_ , that Sam was with Ruby again. He had left to get them some food and had been gone an hour now. Dean slammed his laptop closed out of frustration and at that same moment, Sam walked through the door, a fast food bag in hand.

“Did you have to go to the other side of town to get the burgers or something?” Dean didn’t want to start a fight but he couldn’t resist saying _something._

“It’s almost midnight, dude, nowhere was open. I found this little 24 hour place eventually.”

 _It wasn’t almost midnight when you left_ , Dean wanted to say but he held himself back.

“Whatever man, just give me some food, I’m starving.”

Sam walked over and set the bag down on the table across from where Dean was sitting. As Sam was taking out the burgers and fries, Castiel appeared out of thin air next to the table. Dean almost jumped out of his chair, Sam dropped the burger he was holding.

“Dammit Cas, a little warning wouldn’t hurt,” Dean told him.

“No time, this can not wait,” Cas replied.

It was now that Dean noticed that the angel looked very anxious and was dying to tell them something.

“Alright then, out with it.” Dean had never been much of a patient person.

“We believe that Lilith is on the move again and is going to be attempting to break another seal. There is a string of demonic activity in a place where we have not seen any for a very long time.”

“What place?” Sam asked.

“Now I know this is far beyond your usual travels, but this simply cannot be ignored…” Castiel hesitated.

“Cas, where?” Dean asked impatiently.

“London.”

**London, England**

It was a quiet evening at 221B Baker Street. Or, as quiet as it can get for Sherlock Holmes and John Watson.

Sherlock and John were both sitting in their chairs on their laptops. John was updating his blog and Sherlock was playing solitaire for lack of anything better to do. Having beaten the game twenty times in the past ten minutes, he was getting bored. He started tapping his foot on the floor, and then his fingers against the laptop, loudly.

“Sherlock,” John said after about two minutes of tapping. 

Sherlock appeared to be ignoring him.

“Honestly, we just got done solving a case yesterday and you’re bored already?”

Sherlock looked up. “Really John, that case took me exactly twelve hours to solve. A woman murdered, short list of suspects and she had just cheated on her mentally instable boyfriend. Anderson could have solved it.”

John raised his eyebrows.

“Ok, maybe not Anderson.”

John laughed and shook his head. “Well let’s at least have a break for one day before we go looking for another case, shall we? Some sleep tonight will do you good.”

Sherlock rolled his eyes. “Boring.”

At the next moment, Sherlock’s phone started ringing. He stared at it and John gave him an _are you going to answer that?_ look. He didn’t, until the last ring when his curiosity finally got the better of him.

“Ah Mycroft, to what to I owe the displeasure?”

“I have a case for you.”


	2. Chapter 2

"London? As in London, England? You can’t be serious.” Dean said. They had never traveled to another country before, mainly because Dean hated flying. Now they had Cas to zap them places but he was still uncomfortable about traveling across the ocean.

“As I said, we simply cannot ignore this. I do not know why Lilith would be in London but it cannot be for something good and we have to find out,” Cas replied.

"Are you going to at least tell us what's so important that we have to travel to the other side of the world?" Dean asked. 

"We don't have time, I will explain everything when we get there," Cas answered. 

Dean sighed. “Let's pack our shit then.”

~~~

About a half hour later Sam and Dean found themselves instantly appearing in a London alley way thanks to Cas.

Dean looked around. “So this is London?”

“Yes,” Cas replied. “We are about in the center of the city. There is a motel around the corner we can check into. You two should go do that while I go see if anything else has been happening. I will fill you in when I get back.”

And with that, Cas vanished.

“Huh,” Sam said looking around. “I expected it to feel different. You know, traveling so far.”

“I guess the angel mojo works the same way all around the world,” Dean replied.

They walked down the alley which opened into a bust street. Immediately to their left there was a sign that read ‘The Sleeping Beauty Motel’.

“Are you serious? Who names a motel that?” Dean said in disgust.

Sam laughed. “Who cares, let’s just go.”

They went into the motel and checked in where they were given a key to a room on the first floor. The room was not much different than the motel rooms they were used to. In fact, it was even a little nicer than usual. It had a small round table and a couch and adjacent to that were two queen sized beds. They set their stuff down and waited for Cas, who appeared in the room about five minutes later.

“Nothing else big has happened yet. Now, what happened is this; an undercover detective was murdered, in his own office at New Scotland Yard. The door was locked and no one saw anyone enter or leave the his office that night. Also, no one can think of any motive that anyone would have for doing this. The man mostly kept to himself but he was a nice guy. No reason for anyone to want to kill him."

"Ok hold up, what's New Scotland Yard?" Dean asked. 

“The Metropolitan Police Service, they police the majority of London. It’s one of the most secure places in the country, this kind of thing has never happened before.”

“Maybe a cop just went berserk. You know, had enough. Wouldn’t be the first time,” Dean said.

“If that was the case, why would he murder another cop? Why wouldn’t he just kill himself?” Sam replied.

Cas nodded. “Exactly. Which is why we need to investigate. It had to have been a demon, one of Lilith's demons, the angels have caught scent of her in the area. But the question is, why? This man was of no importance other than being a detective. I do not see a reason why the demons would go after him. My theory is they are trying to infiltrate New Scotland Yard. They basically run the city of London. If you get enough demons in there…they could take over the whole city.”

"Why murder a man though?" Sam asked. "What good does that do?"

"A distraction," Cas replied. "Just another theory. A case like this has the head of every department involved. The demons can slip under the radar. Perhaps their strategy is to start small and work their way up."

“Well then. Let's go check it out,” Dean said.

~~~

“Mycroft for once your call is bringing a smile to my face. We should definitely mark this one on the calendar. Let me hear about this case,” Sherlock said into the phone.

There was a sigh on the other end. “There has been a murder at New Scotland Yard.”

At this, the smile vanished from Sherlock’s face. “Who?”

“No one you knew, his name was Andy Clain. He was an undercover detective. Lestrade knew him. Not very well but none the less.”

“Why hasn’t Lestrade called me?” Sherlock demanded.

“He’s very busy dealing with things down at the Yard. You’re not always the first thing to cross his mind, you know. Especially with something this personal to him. Anyway, the mystery of it is, Clain was killed in his own locked office, no witnesses saw anyone enter or leave the office, no one had any motives. Clain was a quiet man, kept to himself. He was nice though, everyone liked him. No one can figure out why anyone would murder him. So, they called me to investigate. I'm running background checks and investigating every person with access to that part of the building but, and it pains me to say this, crime scenes are your thing and you're quite good at it. I hope you'll be able to make sense of some of this."

“We’re heading down there now, let them know we're coming,” Sherlock replied, hanging up the phone and practically jumping out of his chair.

He ran to get his coat and scarf and came back into the living room. This took about twenty seconds and Sherlock looked exasperatingly at John who was still sitting in his chair.

John raised his eyebrows at him. “Um, care to fill me in?”

Sherlock sighed and repeated everything that Mycroft said at rapid speed so that John’s brain was working at supersonic speed to try and keep up but he caught the basic idea. Within another two minutes both men were dressed and heading down the stairs and out the door. Sherlock hailed a cab and they were on their way to New Scotland Yard.

“I don’t understand it,” John said in the back of the cab. “Why would an officer want to murder another officer? And why Andy Clain? I mean it’s not that he held a high ranking or did anything extremely important. Why him?”

Sherlock didn’t answer, he was asking himself the same questions in his head but he couldn’t determine a reason either.

“I have to see the crime scene and the office before I can make any conclusions,” he finally replied.

The ride to New Scotland Yard took about ten minutes. Entering the building wasn’t too much of a problem, as Sherlock and John were there a lot. They were directed to the second floor, east wing. They headed that way and were met with quite a scene. Officers were everywhere, in the hallway and in the office itself. From a distance Sherlock could see that the door was blocked off with yellow caution tape. Officers were surrounding the dead body on all sides, making it impossible for Sherlock to see what was going on.

They found Lestrade standing just outside the door, observing what was going on and occasionally giving orders. He nodded to Sherlock and John as they approached.

“I’m sorry I didn’t call you myself, Sherlock. Its just been so chaotic around here and I thought it was better to call Mycroft so that he could run background checks and everything. I just can’t figure out who would do this.”

“It’s fine Lestrade, we’re here now,” Sherlock replied.

“And we’re going to figure out who did this,” John added.

Lestrade nodded and smiled weakly at them. “Go on in.”

So they did. Upon entering the office, the other officers realized who they were and backed away. At least everyone did except for two men in suits who Sherlock had never seen before. These men were bending over the body, examining it as well as poking and moving it! Who the hell were these men and what were they doing here and who had given them permission to touch the body before Sherlock got there?! Sherlock was furious and he didn’t know the answer to these questions but what he did know was that this was his crime scene.

**Notes for the Chapter:**

> Hmmm, who are the two men in suits? ;) 
> 
> As always, feedback is greatly appreciated!


	3. Chapter 3

**Notes for the Chapter:**

> Hello everyone! I'm so sorry this took so long! I just got back from a trip to Chicago, which was so much fun but now I'm back so I hope you all like this update, I'm pretty proud of it! :)

Sherlock cleared his throat and drew himself up to his full height. “Excuse me, I don’t mean to be rude but, um, who the hell are you guys and what are you doing at our crime scene?”

The taller man just raised his eyebrows but the other stepped forward and dug a police badge out of his jacket pocket which he held in front of Sherlock’s face. “Excuse _me_ , but we’re here to investigate this crime scene, we’re from the organized crime unit, and you are?”

            Sherlock narrowed his eyes at this man who was too cocky for his own good. “You’re Americans, did you get transferred to another country?” Sherlock asked, trying to throw the man off. They were very good at pretending.

“That’s exactly what we did and this is really none of your business, so maybe you and your friend should…”

“Now hold on.”

“Dean.”

John and Sam interrupted Sherlock and Dean at the same time before they could start punching each other. John spoke next.

“Clearly there’s been a mistake here but we’re not going to solve anything by standing here and arguing about it so maybe we should try to work together.”

“Together?” Sherlock looked at John like he had personally insulted him.

“Sherlock, just this once. We’ll get it straightened out later. Don’t you want to solve this case?” John said under his breath.

Sherlock sighed dramatically. “Fine. Just this once.”

He turned back to the other two men with a fake smile plastered on his face. John thought he looked constipated and tried not to laugh.

“Alright, since it seems we have no other choice, I will be as pleasant as I can. My name is Sherlock Holmes and this is my friend and colleague, John Watson.”

“Ok, I’m Dean and this is my partner, Sam,” the shorter man introduced them.

Sherlock nodded and walked around the desk and observed the body. “Ok gentlemen, you go first, what do you make of this scene?” Sherlock addressed Sam and Dean.

Dean glared at him, not really knowing what to say because he knew what the cause of this man’s murder really was but he couldn’t just tell these guys that. “Oh no please, you go first. I insist,” he said with a fake smile of his own.

“Oh I was so hoping you would say that,” Sherlock said, this time with a real smile. “This man was in his late 30s, unhappily married, two kids. He loved his kids but was unhappy with his marriage to his wife. He was having an affair, probably for about the past six months. You might think his wife would be the first suspect but that is highly unlikely considering it is very hard for anyone other than employees to enter this building. No, the murderer had to have been another employee. The only way in would have been to pick the lock but that is also unlikely because when you pick a lock, it makes some noise, which he would have heard in this quiet office and he was murdered still sitting at his desk. Only other explanation? The murderer was someone he knew, who he willingly let into the office. Anything to add, gentlemen?”

Sam and Dean stared at him. “How the hell did you…” Sam started to say.

“How did I know all that? Well I’m already showing off, might as well keep going. His age is obvious, I can tell by looking, as well as the picture of the two kids on his desk. His wedding ring has been regularly removed, it’s clean on inside but not on the outside, and it’s starting to lose its shine by being regularly worked off his finger but only slightly, indicating a time period of about six months. He works mainly at his desk so he had no other reason to regularly remove the ring. We are on the twentieth floor so it is highly unlikely that anyone climbed through the window and even if they did it would have been impossible for them to do so without Andy Clain noticing. Anything else?”

Sam and Dean were still staring at him. John was trying his best not to smile.

“That was…what the hell was that?” Dean said angrily.

“What do you mean? I merely observed,” Sherlock replied.

“It’s um, kind of what he does,” John offered as a better explanation.

“Sam, can I have a word with you? Privately?” Dean asked through clenched teeth.

Sherlock did nothing to attempt to hide his smirk while Sam and Dean went out into the hallway.

“Who the hell does that guy think he is? He has no idea what’s really going on, let’s just get out of here,” Dean started to walk away but Sam grabbed his arm.

“Look, I know the guy’s kind of a dick…”

Dean raised his eyebrows.

“Ok he’s a major dick. But he might be able to help us, we can use him,” Sam said.

“Please explain before I punch you in the face,” Dean said, not convinced.

“This guy is clearly very smart, we never suspected that the person that the demon possessed was probably someone he knew, so maybe that person remembers something or is still possessed. We can find out who Andy Clain knew personally and maybe we can find our demon,” Sam explained.

“Ok fine so he helped us once, we don’t have to keep him around,” Dean said.

“Dean, if he helped us once, he might be able to help us again. He doesn’t have to know what’s really going on but maybe he can help point us in the right direction and we can catch the demon.”

“Alright alright, fine. But I’m not going to like this.”

Sam and Dean walked back into the office. Seeing the look on Dean’s face, Sam decided he should be the one to talk. “Look, that was…pretty amazing…”

“I know,” Sherlock interrupted.

Sam looked at him. “ _Anyway_ , we think that working together would benefit all of us and help this investigation go a lot faster.”

Sherlock considered this. He really did not want to work with these men, especially Dean, but they did have some very convincing fake ID badges that would certainly fool anyone else. Maybe they could help him get into some of the more secure parts of the building without having to argue with Lestrade. And they were clearly good fighters so maybe they could be physically useful. For these reasons and to avoid a fight, he decided to agree.

“Alright boys, partners,” Sherlock said.

After a moment of awkward silence, John held out his hand for Sam and Dean to shake and nudged Sherlock to do the same. The four of them shook hands and made plans to meet and investigate possible suspects the next day.

Sam and John left the office first. As Dean was walking out, Sherlock put his hand on his arm and leaned in close so that Sam or John wouldn’t hear. “Those fake ID badges might fool most people but they don’t fool me. You two aren’t from Scotland Yard, you aren’t even from this country and that’s not all I know. Two brothers traveling to England just to investigate a murder? One thing I don’t know is who you two really are but I can’t wait to find out.”

With a smirk and a wink, Sherlock walked out.


	4. Chapter 4

“We are fucked. We are so fucked,” Dean said as he paced back and forth in the hotel room.

“Dude, just relax,” Sam replied. He was sitting on the bed watching Dean pace.

“How can I relax? That guy knows, he knows everything. He’s going to bust us and this whole thing is screwed. It was nice knowing ya Sam, because the world ‘s going to end!”

After the scene with Sherlock, Dean and Sam booked it out of the building and they came back to the hotel where Dean had told Sam all about the exchange.

“Look, if he had told the cops right away they would have busted us before we left that building. He’s too intrigued.”

“What do you mean intrigued?” Dean asked, exasperated. He didn’t understand how Sam could even begin to understand what went on inside this Sherlock character’s mind.

“He’s a cocky little asshole and he wants to find out about us for himself. He’s not going to run to the police and just let them arrest us. He has way too much pride for that.”

Dean stared at him. “Whatever man, can we please just find this demon and go home and just say screw this Sherlock guy.”

“We’re supposed to meet up with him tomorrow, if we blow him off he’ll be pissed,” Sam said.

“Ok then let’s go out and find him tonight. Have you been doing your research on this Andy guy?”

Sam sighed and opened his laptop. “I have a list of all the people he worked with in the past couple years so we can start there.”

They went to see three different men who had worked with the victim but all three proved to be harmless with no sign of demon activity and there were still five other men and two women on their list.

“Alright, who’s next?” Dean asked with a sigh. They had been walking pretty much everywhere because they weren’t used to flagging down cabs and they weren’t very good at it. They were now stuck on a side street because the main road wasn’t getting them anywhere. “Where are we again?”

“Um…Baker Street,” Sam said looking at a sign.

“That tells me absolutely nothing,” Dean replied. He pulled out his phone and opened up the GPS trying to figure out where the hell they were.

“Lost?” A voice said from behind them.

Sam and Dean whipped around. Sherlock Holmes was standing on the doorstep behind them with his hands in his pockets and an amused expression on his face.

“No, we were just…” Dean started to say.

“Lost,” Sherlock finished for him. “Trying to find the murderer without me?” He came over and took the list out of Sam’s hand and shook his head. “You could narrow this down considerably if you knew that the killer was in his 30s, average height, and size 10 feet.”

Sam and Dean just stared at him. Dean looked like he wanted to punch Sherlock in the face and Sam looked mildly impressed.

“Now that we’ve established that you two need me, won’t you come in? I just made tea.” He walked back into the flat and turned around when he saw that Sam and Dean weren’t following. “Unless of course you’d rather wander the London streets with no clue where you are.” With that he walked into the flat, leaving the door open.

Sam sighed and followed Sherlock and Dean threw up his hands with no choice but to follow. They followed Sherlock up a set of stairs and into a rather messy but nice looking room. John was sitting in a chair on his laptop and raised his eyebrows at the sight of Sam and Dean.

“These two found themselves lost and right outside of our flat. I’ve invited them in for tea,” Sherlock said with a smile.

“Right,” John replied, still looking confused.

“Jesus, all those British stereotypes are real,” Dean muttered under his breath.

Sherlock walked out of the kitchen with the tea that he promised and handed a cup to Sam and Dean then brought out two more cups for John and himself. Sherlock settled himself into his chair across from John, leaving Sam and Dean standing awkwardly in the middle of the room.

“Excuse his manners, please pull up a chair,” John said gesturing to the chairs surrounding the kitchen table.

Sam and Dean did as they were told. There was an awkward silence as Dean and Sam stared skeptically into their tea.

“Oh please, if I wanted to poison you two, you’d be dead already,” Sherlock said as he calmly sipped his tea.

“Again…manners, but he does have a point,” John replied at Sam and Dean’s expressions.

“Now,” Sherlock said setting down his tea. “About the case, I’ve narrowed the list of suspects down to…”

Sherlock was cut off by a knock on the door. “Clients are supposed to call first,” Sherlock grumbled as he got out of his chair to answer the door.

He walked to the door at the top of the stairs but before he could open it, it was thrown open and Sherlock was thrown to the floor. John, Sam and Dean all jumped out of their chairs. A man and a woman walked in with smirks on their faces. Before anything else could happen, the man raised a hand and John and Sherlock were thrown against the wall and held there. The woman did the same to Sam and Dean and threw them against the opposite wall.

“We heard you two were on the hunt for Lilith,” the woman said as she advanced toward Sam and Dean. “It would be wise for you to give up now, we’d hate for anything to happen to you two new friends,” she said glancing toward Sherlock and John.

The man chuckled and twisted his wrist. John let out a cry of pain which turned into a scream as the man twisted his wrist further.

“Stop! What are you doing? Stop it!” Sherlock cried.

“Enough!” Dean yelled.

The woman held up her hand and the man dropped his arm. John let out a cry of surprise and was breathing heavily. Sherlock had no idea what to do, he was still pinned against the wall by an invisible force.

“They have nothing to do with this, leave them out of it,” Sam said.

“Oh Sammy, if only it were that easy,” the woman said. “You two should have never came to England, you should have stayed in America where you belong.”

She took another step toward them and then Cas appeared out of nowhere behind her. She turned around in surprise and Cas put his hand on her forehead. With a scream and a flash of orange light, she fell dead onto the floor. The other demon growled and ran toward Cas. Cas dodged him, kicked him in the stomach, and put his hand on the demon’s forehead, also killing him.

Sam, Dean, Sherlock and John all fell on the floor. John was still moaning in pain. Sherlock rushed over to him. “What did they do to him?” Sherlock was panicking, he had no idea what just happened or how to stop John’s obvious pain. There was no wound and Sherlock didn't know where the pain was coming from.

Cas walked over. “He’ll be alright,” he said to Sherlock. He put his hand on John’s forehead and the pain stopped.

After that, there was an uncomfortable silence. For once in his life, Sherlock was speechless. He and John stared at Cas with astonishment.

Cas turned to Sam and Dean. “I believe we have some explaining to do.”


	5. Chapter 5

**Notes for the Chapter:**

> Well this chapter was definitely the hardest to write so far because it was really hard imagining how Sherlock would react to angels and demons lol. But I had a really fun time writing it and I just wrote it the way I imagine it so I hope you all like it :)

Sherlock and John stared at Cas for another five minutes. John was feeling his chest area, expecting to still be in pain as it had seemed to magically go away. Sherlock looked back and forth from John to Cas, concerned about John and in awe of Cas. Finally he had to say something, so he did.

“Can someone please explain to me what the _hell_ just happened?” There was still a hint of panic in his voice, John continued to say nothing.

Cas opened his mouth but Sherlock interrupted. “Who are you?” he asked pointing at Cas. He then turned to Sam and Dean. “And who are you guys? Who are you really? Because I _will_ know if you’re lying.” He was standing now, looking back and forth between the two men and one angel.

“I’m an angel of the lord,” Cas said.

“Come again?” John spoke.

“An angel,” Cas repeated.

“Like a Christian or Jewish angel?” Sherlock asked after a long pause.

Cas looked puzzled. “I have limited knowledge on different humans’ religious beliefs. Allow me to show you.” Cas stepped back and there was a flash like lightening. Cas’ eyes rolled back into his head and a black shadow in the shape of wings appeared on the wall behind him. This lasted for about 30 seconds and the wings disappeared and Cas stood there like nothing had just happened.

John stared at him open mouthed and Sherlock stood with his hand on his chin, thinking. “So angels are real. I have read many stories but was never a true believer seeing as how I’ve never seen one in person. Very interesting indeed,” he said.

“You’re taking this rather well,” John said in a higher pitched voice than normal.

“Everything has the power to exist, John. Anything and everything has a possibility of existing. It’s only a matter of believing or seeing,” Sherlock remarked.

“Ok Sherlock, I just…I need a moment,” John replied.

Sherlock did not acknowledge this comment. “And they are…?” he asked, gesturing to the two bodies on the floor.

“Demons,” Cas sad.

“Of course,” was all Sherlock said.

“Ok Cas, you’re not helping,” Dean said, stepping forward. “Basically, everything you’ve ever had nightmares about, all the lore you’ve ever read, everything is real. Angels, demons, ghosts, vampires, werewolves, you name it.”

“So angels can kill demons?” Sherlock asked. “How can that be? Aren’t they both of equal power? Angels are second to God and demons second to the devil basically.”

“I’m sorry, since when did you become an expert on this stuff?” John asked. Sherlock just smiled at him.

Religion and lore was never something Sherlock took a big interest in but he had it stored in a corner of his mind palace in case it ever came in handy. Now he was glad that he hadn’t erased it.

“God, therefore angels, will always be superior to Lucifer and his demons. They are all extremely powerful but remember that Lucifer was an angel who God cast out of heaven. Therefore God will always be the most powerful,” Cas said.

“I understand,” Sherlock replied. “So you guys are on a hunt for some demon, then?” he asked.

Castiel, Dean, and Sam proceeded to tell Sherlock and John about Lilith and the threat of the apocalypse.

“So this is what you guys do with your lives?” Sherlock asked after they had finished their explanation.

“No one else will do it,” Dean said.

“So let me get this straight,” John said. “The two of you travel around the world hunting demons and ghosts and other supernatural creatures with the help of an angel. Meanwhile Lucifer and this demon Lilith are attempting to start the apocalypse ? The actual, biblical apocalypse?”

“Yeah, basically,” Dean said.

During this whole thing, Sherlock seemed to be listening with genuine interest. “So how do you guys fight these things? I mean, how do you fight a demon?”

“Before we go on, tell me something,” Dean said.

“What’s that?” Sherlock replied.

“What is it that you two do? I mean at first I thought you could read minds or something but then I slipped some holy water in your tea. How did you know about me and Sam and everything else?”

Sherlock chuckled. “I simply observe everything and deduce results from what I observe. For example, I observe that there is a small bulge on the left side of your jacket in the shape of a shot gun and that you are sitting slightly forward on your chair with a slight tension in your shoulder and your right hand is angled up slightly, ready to reach for the gun if needed. But the chances of you needing to pull out a shotgun in the middle of this flat are very low. Therefore I can deduce that you are a man who is always prepared for the worst but prepared nonetheless and ready to expect anything. You are also good at hiding things and have experience with guns and how to use them.”

“Wow, that’s um, that’s right. Kind of makes me want to punch you a little bit but still.”

John laughed. “Don’t worry, that’s how everyone usually feels.”

“As for what I do, I am a consulting detective. The only one in the world. The police consult me when they are stuck, which is what they did yesterday with Andy Clain’s murder. Now please, tell me more about these supernatural beings. I haven’t had the opportunity to learn something new in a very long time.”

Dean sighed. “You know, a person gets kind of tired of explaining things after a while.”

Sam laughed and pulled out his laptop. “Come on, I’ll show you some of my websites that I do most of my research on.”

Sherlock looked delighted and went over to sit with Sam. Dean muttered a nerd remark under his breath and turned to John.

“So you like tag around with this guy? Help him solve crimes and shit?” Dean asked.

John laughed. “I guess you could say that. He really is an amazing guy once you get over…you know. It’s really amazing, what he can do, never fails to impress a person. Anyway, we really can help, you know. Both of us know London really well, it will make your search a lot easier if you actually know where you’re going. We can also get you into New Scotland Yard and we know a lot of people there. And as you’ve seen, Sherlock is really smart. We may be new to this supernatural stuff but we’re not completely useless by any means.”

“Ok, I’ll admit you’re right,” Dean said. “But even so, why do you want to get involved in this? Most people would be terrified. Some would call chasing after a demon a suicide mission.

John chuckled and cast a sideways glance to Sherlock. “I’ve been told I have somewhat of an adrenaline addiction.”  


	6. Chapter 6

As Sam was telling Sherlock about demons, John’s curiosity got the better of him and he went over to listen while Dean rolled his eyes and started a conversation with Cas. Sam explained to Sherlock and John all about demons and how to hurt or kill them. He told him about salt, holy water, devil traps, and exorcisms.

“Can you read Latin?” he asked Sherlock.

“Of course I can read Latin,” Sherlock said, as if reading Latin was common knowledge.

Sam pulled up another page on his laptop and there was the exorcism chant. Sherlock scanned it for about five minutes. In these minutes he had read it, memorized it, and translated it.

“Got it,” Sherlock said after he was done.

“What?” Sam said, confused.

Sherlock smiled, turned away from the laptop and repeated the exorcism, word perfect.

“Wow. Um, nice, good. That might come in handy,” Sam said, looking impressed. Even Dean raised his eyebrows at Sherlock’s memorization ability.

“So that will kill a demon?” Sherlock asked.

“Technically, no. It sends them back to hell but it gets rid of them nonetheless.”

“How can you kill them?”

“With this,” Dean said, pulling out Ruby’s knife.

Sherlock looked intrigued. “May I?” he asked, holding out his hand.

Dean hesitated but then placed the knife in Sherlock’s hand. Sherlock examined it, running his fingers along the symbols on the blade and studying them. “These symbols must be thousands of years old,” he muttered.

“Right you are,” Dean said, taking the knife back.

“Where did you get it?”

“A demon. Please, don’t ask,” Dean added when Sherlock opened his mouth again.

Sam fell silent, knowing it was probably not the best time to mention Ruby to them.

“Ok, if we’re done with our little nerd fest, we should really leave,” Dean said after a moment of silence. “If those demons knew we were here they’re certainly not the only ones. We’re not safe.”

“He’s right,” Cas said. “We can go back to the motel. Have you figured out who killed Andy yet?” he turned to Sherlock.

Sherlock looked surprised at first but then nodded. “I believe I have.”

“You have?” John asked in surprise.

“Do keep up, John,” he said with a wink. John rolled his eyes.

“Can someone fill me in?” asked a frustrated Dean, also trying to keep up.

Sherlock explained. “I looked at the data from my observations at the crime scene. Cross referenced that with the all people that Andy Clain knew and then those people who had access to that part of New Scotland Yard. I came up with….” he paused to run over to his laptop and push a few buttons on the keyboard. A page came up with a picture of a man and the name David Smith under it. The man was young looking with disheveled brown hair and brown eyes. “David Smith, age 36. Worked with Andy in an undercover project in 2010 for about a year and a half where they became quite good friends. They still work together, pretty much partners just not officially. On top of everything else, no one has seen David since the day before the murder. They think he’s just too upset to return to the office.”

“So Andy would have let David in his office without question,” Sam said. “And then he killed him.”

“But it wasn’t really David, was it?” John said.

“No,” Cas said. “He was possessed and with any luck, still is.”

“Great, now we just have to find him. He could be anywhere,” Dean said.

“Well I have his address,” Sherlock replied, pointing to his laptop. Sure enough, under basic information, it listed David’s address.

“You hacked into the police databases,” Sam said, realizing before Dean did how Sherlock had this information.

“Yes,” was all Sherlock said.

There was a pause and then Dean laughed. “Nice,” he said. The corner of Sherlock’s mouth turned up in what was almost a smile.

With that, the five of them got ready to leave. John picked up his pistol from where he had laid it on the table next to the couch.

“An ordinary gun probably isn’t going to be much help,” Dean said.

“We never go anywhere on a case without them,” Sherlock said pulling out his own gun from inside his jacket.

Dean smiled. “Smart. I admire that. We’ll get you guys some useful weapons when we get to the....” he had a sudden realization that they were now in London.

"Don't worry, I've brought it here too," Cas said with a smile.

"Cas, you're the best," Dean told him. They left the flat and with some guidance from Sherlock and Cas, Dean managed to find where the impala was parked.

“You care deeply about this car,” Sherlock observed while looking the car over.

“No shit, Sherlock,” Dean replied.

They drove and parked down the street from David Smith’s house. Dean opened the trunk and handed Sherlock and John shotguns loaded with rock salt. He also gave them two flasks with holy water. After they had their weapons, Dean drove to the front of the house so that they could stake the place out before going in.

Sure enough, there was David Smith in the kitchen. He was walking back and forth and appeared to be talking to someone out of sight. There was no sign of a wife or kids, both of which he was supposed to have. At the next moment, David turned, just briefly to where the impala was parked.

“Shit,” Dean hissed. They all pretended to look natural and Dean pretended to fumble with something in the car.

“Does he know?” John asked.

No one replied. Dean turned very slowly to look out the window again. At first, there was no indication from David that he had noticed them. But then he turned to whoever he had been talking to with an evil smirk that made all of their stomachs turn. The other man, who had been sitting at a table, stood up to stand with David in front of the window.

John gasped loudly and Sherlock dropped the binoculars he had been holding. There, standing with David Smith whose eyes had turned black, was James Moriarty.

**Notes for the Chapter:**

> In case you were wondering, yes David Smith is a combination of David Tennant and Matt Smith because they're my babies and coming up with names is hard.
> 
> Also I wish I could have made this chapter longer but don't you just love how it ends?


	7. Chapter 7

"Go! Go!” Sam shouted.

Dean didn’t have to be told twice. He stepped on the gas and they were speeding up and down the London streets. Sherlock seemed to be in a state of shock. His eyes were darting around everywhere, seeming to expect Moriarty to magically appear somewhere on the side of the road. Just then Sherlock’s phone beeped with a text alert. The noise he made was somewhere between a growl and a gasp as he dug his phone out of his jacket pocket.

_IOU_

_-JM_

Sherlock could have screamed. Instead he rolled down the window and drew back his arm.

“Sherlock!” John realized what he was doing a second before he did it and grabbed the phone out of his hand. “What are you doing?”

Sherlock turned to face John faster than John could properly react and grabbed him by the shoulder. “Do you not understand what’s happening? Moriarty on his own and with his web is bad enough. Moriarty consulting with…demons,” he spat out the word. “That’s our worst nightmare.”

“Wait, you guys know that other dude?” Dean asked from the driver’s seat. He was still driving along but not as fast as before. There didn’t appear to be anyone following him but you could never be too sure.

“Of course we know him,” Sherlock replied.

Dean raised his eyebrows, but there was no response from Sherlock so he let out a loud sigh before he spoke. “Who is he?” he almost shouted.

“James Moriarty. The most dangerous criminal the world has ever seen.”

“Most dangerous human criminal,” Cas corrected.

“Lovely…that’s just, that’s awesome,” Dean said.

“Is he possessed then?” Sam asked.

“I doubt he would need demonic possession,” Sherlock said.

Cas jumped in his seat just then. Dean noticed. “What is it?”

“Something is happening. I’ll be right back.” Cas vanished.

Dean threw up his hands. “I don’t think I’ll ever get used to that,” John mumbled.

Dean suddenly pulled the car over and stopped. “Wait a minute why the hell are we running? We know where they are, we’ve got weapons. Let’s drop these guys off and go get those bastards!”

“Excuse me?” Sherlock seemed to have snapped out of his shocked phase and was now looking at Dean like he was absolutely insane.

“What? No. No way. You’re not coming.”

“Don’t you see?” Sherlock leaned forward in his seat, getting in Dean’s face. “You cannot even begin to know Moriarty like we do. He’ll mess with your mind, he’ll trick you. He’ll lower you right into whatever trap they’ve set and he’ll do it easily.”

Dean scoffed. “I think we’re a little smarter than that, buddy.”

“No, you’re not,” Sherlock replied.

Dean looked like he wanted to punch him. “Dean,” Sam warned.

“Look, the demons may be your problem but Moriarty is ours and this is _our_ city that they’re threatening,” Sherlock said. “And if you don’t want us to come with you, we’ll just go ourselves. Come, John.” 

With that, Sherlock got out of the car. John gave Dean and Sam an apologetic look and joined him.

“Fine,” Dean said, mostly to himself. He moved to shift the car into drive but Sam stopped him.

“Dude, we can’t just leave them.”

Dean gave Sam an _are you serious_ look and Sam just raised his eyebrows at him and gave him his best bitch face.

“Son of a bitch,” Dean muttered, getting out of the car. Sam followed.

“Look guys,” Sam started, but then he stopped mid-sentence. There was a group of people walking down the street towards them. Leading the group was a blond little girl.

“Run!” Dean shouted.

The four of them took off running in the opposite direction. They turned a corner and almost collided with two more smirking demons. They booked it in another direction. “Let me!” Sherlock shouted, pushing past Dean to lead the group. They ran down alley ways and side streets, the demons were still right behind them. “In here!” Sherlock tore open the door of an old abandoned warehouse.

“Did they see us come in here?” John panted, out of breath.

“I don’t know,” Sherlock replied.

Dean pulled a crow bar out of his pocket and shoved it in the door handles. “If they know we’re here that won’t hold them off for very long.”

“There’s another door, on the other side of the building,” Sherlock said.

Since it was a warehouse, said building was huge and there were a lot of obstacles in their way like pieces of wood and concrete and old junk that was just left there when the warehouse closed. However, the building was long and narrow, not wide so they at least couldn’t get separated. There were only a few feet between them and the door now.

Sherlock saw it coming before anyone else but didn’t have time to say anything or even shout a warning. The door was thrown open and three demons walked in, two men, one with dark black hair and another with blond, and a blond woman. One of the men raised his hand, the other grabbed Sherlock and pulled him back roughly, and then the ceiling collapsed right in front of them.

“John!” Sherlock shouted. Oh God. Had the ceiling crushed them or were they able to jump back in time? He didn’t care about the demons right now, which were standing behind him, laughing.

“He told us that you love to complicate things,” the man with dark hair said.

“Moriarty,” Sherlock stated. He wasn’t afraid. Not yet anyway. If they had hurt John…

“Right you are,” the man answered.

Sherlock forced out a laugh. “So predictable. Monsters invade London, of course the city’s most dangerous criminal would join up with them.”

“Yes. Just as you joined up with the Winchesters. It has made for quite an annoyance, I must say.”

“What do you want with me, then?” Sherlock still didn’t understand why he had been separated from the others.

“Oh honey,” the man purred. “A lot of things. But first…” he raised his hand and Sherlock was thrown to the wall. With a grunt of pain, his head collided with the cement wall and he collapsed to the floor. Before he lost consciousness, he heard John’s cry of “Sherlock!”


	8. Chapter 8

John had been walking a few steps ahead of Sam and Dean when the ceiling came down. They both took a hold of either of his arms and yanked him back; otherwise he probably would have gotten crushed. For a few moments, he just stared at the rubble, not fully understanding what had just happened. The next thing he registered was that Sherlock was no longer with them.

“Sherlock!” he shouted, rushing over to the pile of rubble. He heard voices on the other side but they weren’t Sherlock’s.

“It didn’t fall on him,” Sam assured John, putting a hand on his shoulder.

“Did he jump out of the way?” John asked.

“Well…not exactly. The demons sort of pulled him back, he’s with them.”

John’s stomach dropped. Why had the demons separated them? They could have taken them all out. However, he couldn’t help but thinking _at least he’s not dead._

“Don’t worry, man, we’re gonna get him. I’m going to kill those sons of bitches,” he growled.

Sam and Dean walked back outside and John followed. There didn’t seem to be any sign of demons now. Why were they after Sherlock? John felt like crying but there was no way he was going to do that. If the situation were reversed, Sherlock would have probably figured out where the demons had taken John and been running to save him. But John had absolutely no idea where to even start. He swallowed the lump in his throat.

“Cas!” Dean practically shouted. “Cas, where are you? We need you, man!”

John stared at him. How was Cas going to hear him? But about two minutes later, Cas appeared next to them. John supposed it must be some kind of angel power. Dean rushed to explain to Cas everything that had just happened.

“Please, can you find him?” John sounded desperate but he didn’t care. He just wanted Sherlock back, unharmed.

“Yes. I mean, I already know where he is.”

“Where?” John, Dean and Sam said at the same time.

“They’ve taken him to New Scotland Yard.”

~~~

The first thing that Sherlock became aware of was that his head was pounding. It was antagonizing and he let out a moan of pain. He tried to bring his hand up but found that he couldn’t. His hands were bound behind him. The memory of what had happened came rushing back to him, making his head hurt even more. He remembered the demons, the ceiling collapsing, and being separated from John. _John._ His eyes flew open.

“Well well, look who’s awake.”

A man’s voice. Sherlock slowly looked up. It was the same three demons that had been at the warehouse. Standing next to them was David Smith and Moriarty. There was also a little girl who looked to be about eight years old.

“Hello, Sherlock,” Moriarty crooned as he walked toward him.

He really should be panicking more than he was. In fact, he wasn’t really panicking at all. He supposed since he was just kidnapped by a few demons who were now standing a few feet away from him and John may or may not be dead, this was nothing to him.

“One with the demons, I should have known,” Sherlock said through clenched teeth.

“Hey, I didn’t find them, they found me. But I’m soooo glad that they did. I thought _I_ was capable of doing some crazy things. I had no idea. It’s brilliant, Sherlock, quite brilliant. You’ll know soon enough.”

“What do you mean?” Maybe if Sherlock kept him talking he could postpone whatever they were planning.

Moriarty turned to the demon who was in David Smith’s body. “Why don’t you tell him? He should hear it from a real demon.”

David smiled and spoke. “Well, as you probably already figured out, we have been trying to infiltrate Scotland Yard. It’s been working but we thought, how could we take over the police force and at the same time have Sam and Dean Winchester come running right into a building filled with demons? So, we knew that by kidnapping you or John, the boys would have no choice but to come running to save you because that’s just how they are. And with your superior mind, you were the better candidate.”

Sherlock understood, although he didn’t want to. The demons could use him to get through the Yard and they could easily get close to Lestrade. But he wondered what his mind had to do with it. His puzzled expression must have shown because David started to talk again.

“You see, when a demon possesses a person, they have access to their memories and brain. Therefore, your intelligence will transfer to me.”

 _Possession? No, no, no. Keep them talking!_ Sherlock thought.

Before Sherlock could say anything else, the little girl stepped forward and put her hand on his forehead. Sherlock bit his tongue until it bled to keep from screaming in pain. His headache intensified and just when he thought he couldn’t take anymore, she removed her hand and the pain went back to a dull ache.

“Oh yes, he will do quite well,” she said.

“So this is your big master plan, then?” Sherlock tried to stall them.

“Brilliant deduction. Now, enough messing around,” David said as he walked toward Sherlock until he was standing only a few inches away from where he was tied up. “Don’t worry, you won’t feel a thing.” He grabbed Sherlock by the hair and yanked his head back.

He could see what was happening as it happened. He saw the big cloud of black smoke come out of David Smith’s mouth and go into his own. Then he felt something that he couldn’t even describe. It was pure evil, everywhere, inside him, taking over his mind and body. One of the other demons untied his hands and Sherlock stood up. He was aware of what was happening, of what his body was doing but he couldn’t control the movements. He had not commanded his body to get up, someone else had. He had no idea what was happening and suddenly he heard a voice inside his head.

“I’m doing you a favor, Sherlock. I’m letting you see everything that’s happening. I could push you back and make you completely unaware but this is much more fun. Let’s go see Detective Inspector Lestrade, shall we?

~~~

In a matter of seconds, Castiel had zapped Sam, Dean and John outside of New Scotland Yard.

“The place is surrounded by demons,” he said. “They’ve put sigils on the doors. One of you will have to break them so that I can get inside.”

“I’ll do it,” Sam volunteered. “You should go with John,” he said to Dean.

Dean didn’t know exactly why he was suggesting this but there was no time to argue it.

“Ok, you ready?” Dean asked John.

John swallowed. He would probably never be ready but Sherlock was in there and that was all that mattered. He was at war in Afghanistan for Christ’s sake, he could handle this. Probably. “Ready.”

Dean led John around to the back of the building to the emergency exit. Dean quickly picked the lock and the door open. John wondered why the alarm hadn’t sounded and Dean said they would have disabled all the alarms a long time ago. They slowly walked down the hallway but stopped short when they saw two demons guarding the end of the corridor. Dean motioned for John to follow him and pulled out the demon killing knife. John had to admit he was good at being sneaky. Just as the demon on the left sensed someone coming, Dean jabbed the knife into its back. There was a flash of orange light and the demon collapsed to the floor.

During this time, the other demon was advancing on Dean so John did the only thing he could think to do and threw holy water on him. The demon literally smoked and howled in pain. Dean stabbed it in the chest and it collapsed to the floor next to the other demon. The hallway was branched out in three different directions. Dean looked from one to the next, not knowing where they should go. “Any ideas?” he asked John.

John said the first place that came to mind. “We should try Lestrade’s office.”

Lestrade’s office was on the second floor. John took the lead and they ran as fast as they could up a flight of stairs. “That went better than I hoped,” Dean commented when they reached the top.

“Come on,” John replied. He was really worried about Lestrade now. They ran down the hallway to Lestrade’s office which was nearly at the end.

“Wait!” Dean warned. But John was already to the door of the office, which was open and he stopped short at what he saw. A terrified looking Lestrade was backed up against the wall by a very different looking Sherlock.

Sherlock turned to face John. It was Sherlock’s face and his body but John knew that something was wrong. “Hello, John. How nice of you to join us.”


	9. Chapter 9

**Summary for the Chapter:**

> WARNING FOR THIS CHAPTER: SOME NON/CON (KISSING ONLY)
> 
> I didn't think it was necessary to put an archive warning on the whole story but yeah this is mild and only happens for a second and can be skipped over if needed. :)

John just stood there, staring at this man that was apparently Sherlock. But it wasn’t, he could tell. There was something different about him, a lot different. If someone asked him he probably couldn’t describe the difference in words but he knew Sherlock and he knew that this wasn’t him.

“You’re not Sherlock,” is what he finally managed to choke out.

Sherlock, or demon Sherlock, stepped away from Lestrade and started walking toward John. John thought he looked like a creature stalking its prey but he didn’t back away.

“What do you mean? This is my body, my voice, of course it’s me.”

“Get out of him, you son of a bitch,” Dean growled as he stepped forward in front of John.

Sherlock looked down at the knife in Dean’s hand and smiled. “You should kill me, Dean. You’ve been after me all this time and here I am. Come on, then.”

“No,” John practically whispered. He wasn’t even sure if Dean had heard him. “You can’t kill him. But there are things that won’t hurt Sherlock.”

With the speed of a solider drawing a gun, John took out his holy water flask, unscrewed it, and dumped the rest of it on Sherlock. He howled in pain and John started to back away because it was still Sherlock’s voice and it still sounded like his scream.

“Come on!” Dean grabbed Lestrade’s wrist in one hand and John’s in the other. They ran down the hallway, up two flights of stairs and into an empty room. Dean shut the door and pulled out a bag of salt which he poured along the bottom of the door and on the window sill. They were all panting, trying to catch their breath.

“Is that salt?” Lestrade looked at Dean like he was insane.

“Yes, it is. You must be DI Lestrade, I’m Dean, nice to meet you,” he took a bewildered looking Lestrade’s hand and shook it.

“Just do everything he says, trust me,” John told him.

“What the hell is going on here, John? One second everything is running smoothly and the next….these people have black eyes…or maybe I’m just seeing things,” Lestrade went on.

“Nope, not seeing things. Unfortunately,” Dean said. “Look, all that matters is these things are dangerous and one of them has possessed Sherlock and we have to get it out.”

“Excuse me?” if it was possible for Lestrade to look any more baffled, he did.

“How do we do that? It can be done without hurting him, right?” John asked.

“Of course.” Dean thought for a moment. “I can paint some devil traps in here. Then we would have to get him to come here where we could exorcise it out of him.”

“Ok...good plan but how do we get him in here?” John asked.

“You,” was Dean’s reply.

“No,” Lestrade almost shouted. “John, you can’t risk that.”

“Listen,” Dean put a hand up to silence him. “Demons can feed off people’s memories. He’ll know everything and use it against you. And, he’ll be trying to hurt Sherlock. Demons are able to make the person they’re possessing conscious during everything. He’ll want you, John but nothing’s gonna happen to you. All you have to do is lure him here and everything will be fine. Just let him see you, then run here, and he’ll chase you.”

“How do you know?” Lestrade glared at him. “How do you know this will work?”

Dean walked over so that his face was inches from Lestrade’s. “Because I’ve been dealing with these things my whole life. I watched them kill my family and my friends, I’ve been to hell. I know how they work, alright? And I’ll be damned if I let anyone else get killed tonight.”

Lestrade suddenly seemed to be very interested in the floor. He took a step back. “I’m sorry…about all that. We need Sherlock. But John just…be careful. Please.”

John nodded. “I survived a war. And I survived living with Sherlock Holmes. I’ll be alright.”

Lestrade smiled a small smile. “Here,” Dean said. “Take this.” He handed over the demon knife.

John looked at it. “But you…”

“You need it a lot more than I do right now. You’re a war veteran, I know you know how to use it. Stab anything that gets in your way.”

Most people would have probably been a little horrified by this statement but John wasn’t most people. He nodded and took the knife. He gave Lestrade a nod, took a deep breath, and walked out the door. He walked down the hallway and as quietly as he could down the stairs. He didn’t know if he was prepared to face Sherlock again. The last encounter was possibly the scariest experience of his life.

Sherlock was not evil. Sherlock was Sherlock. Sherlock who would play his violin so beautifully when John was having a nightmare. Sherlock who would litter the kitchen table with various science equipment and put body parts in the fridge and drove John up the wall. Sherlock who would get takeout and make tea after a really tough case. Sherlock who helped John get over his PTSD, psychosomatic limp, and depression.

And his eyes. Sherlock had eyes that a person could get lost in. But when John had looked into them, they were not Sherlock’s eyes. There was something evil there. John was going to get his Sherlock back. This burst of anger pushed him forward and back to Lestrade’s office. He expected to see Sherlock but what he hadn’t expected to see was Sherlock standing next to Moriarty.

“Johnny boy!” Moriarty called. “Just the guy we wanted to see.”

John avoided looking at Sherlock. “What do you want from me?”

“Good question. It’s not that you’re useful to us,” Sherlock spoke and was now walking towards him and John had no choice but to look up. There were those eyes again. John gulped. “But you know, Sherlock’s still in here,” he said tapping the side of his head. “He can see and hear everything going on. He’s begging me not to hurt you.”

John took a step back because Sherlock had not stopped advancing on him. “But you see,” Moriarty spoke. “Sherlock has been very naughty. Teaming up with and helping these Winchester boys. It’s put a very big delay in our plans. We think he has to be punished for it.”

Sherlock took another step forward and John did the only thing that seemed logical. He ran. Back towards the stairs, hoping Sherlock would follow him. He ran up the first flight of stairs and down the hallway to the second flight that would lead him to the floor where Dean was. He stopped at the second flight to risk a glance behind him. Sherlock was still following. He wasn’t even running, just walking and he wasn’t too far behind John. John didn’t know if it was just because Sherlock was so much taller than him or if this was another demon power, not that it mattered. He turned around and got three steps up before he felt Sherlock grab the back of his shirt and throw him backwards to the floor.

John’s breath was knocked out of him and he gasped for air and before he could do anything else and with a speed that he didn’t understand, Sherlock was on top of him, straddling his hips and grabbing both of his wrists in one hand, pinning both his arms above his head.

“John,” Sherlock purred. “I can definitely see why he likes you.”

John tried to pull away but it was no use, demon Sherlock was a lot stronger. John had imagined a few different scenarios where Sherlock was on top of him but none of them were like this, and this was not Sherlock.

“Sherlock, please,” John pleaded. He knew Sherlock was in there somewhere. And he knew Sherlock was a strong guy with a strong mind. Maybe, somehow, he could over power this demon.

Or maybe John was just desperate.

When John looked up again, Sherlock’s eyes were solid black. John gasped and Sherlock took this opportunity to lean down and pressed his lips to John’s and force his tongue inside. John tried to turn away but it was no use. The kiss was wet and sloppy and a little painful. Sherlock pulled away and smiled. “He’s been thinking about doing that for a while…you should hear some of the thoughts he has about you,” he tisked. “But now that we’re past the fun stuff…”

Sherlock reached into John’s pocket and pulled out the demon knife that Dean had given him. “You weren’t going to use this on me, were you John?” Sherlock said holding the knife in front of his face.

“Sherlock, please, I know you’re in there,” John tried again.

Sherlock just smirked at him and leaned down so his mouth was practically against John’s ear. “Sherlock’s gone.” He felt the blade dig into his shoulder.


	10. Chapter 10

**Summary for the Chapter:**

> Only one more chapter left!

John screamed as the demon pushed the blade as far into his shoulder as it would go and then yanked it out. “Stop. Sherlock. Please,” John choked out.

The demon ran the bloody blade across John’s cheek and laughed. “I haven’t even gotten started.”

He raised the knife again but before he could bring it down, something flickered in Sherlock’s eyes and he paused with the knife in midair. John noticed the difference right away and just stared at him. This lasted for about two seconds before they flickered again and the evil look was back. He went to bring down the knife but before he could make contact there was a shout of “hey!” followed by a gun shot. Sherlock was thrown off of John and onto his back on the floor.

John didn’t even have time to be horrified before Sam started chanting the exorcism. What John saw was like something out of a horror movie. Sherlock’s body jerked like he was having a seizure and he kept letting out these screams and gasps of pain. As Sam ended the chant, Sherlock jerked his head back and a cloud of black smoke came out of his mouth and disappeared somewhere into the ceiling and Sherlock’s body slumped back and onto the floor, apparently unconscious.

“Sherlock!” John rushed over to him. His eyes were closed but his chest was moving up and down and he was breathing. John noticed the difference immediately. Sherlock’s face was calm and when he opened his eyes after a few minutes, they were Sherlock’s eyes again.

He blinked and looked and John then over at Sam and Dean, who was still holding his shotgun, then eventually back at John. “Your shoulder…”

In the moment of chaos John had almost forgotten. Now that Sherlock had said something it was actually quite painful and gushing blood. He took Sherlock’s scarf from around his neck and tied it around the wound to stop the blood flow.

“Man, we need to get you to a hospital,” Dean said walking over to them.

“No,” John shook his head. “I’m a doctor, I can do stitches with my eyes closed,” he told them.

“Fair enough because so can we,” Dean said with a smirk. “Come on we have to get out of here. Also, where the hell is Cas?” he asked looking over at Sam.

Sam shrugged. “I broke all the sigils that I could find. Unless I missed one but that’s unlikely.”

Dean frowned. “Well come on, we can worry about it later.”

They started walking, John holding his shoulder and Sherlock looking a bit unstable and kept glancing over at John thinking he didn’t notice. They made it all the way to the front door and Moriarty was blocking the exit. He looked as calm as ever, in a brown suit and arms crossed over his chest.

“What a shame, I liked you much better as a demon,” he said looking at Sherlock, who visibly flinched.

Dean sighed. “You obviously have no idea about the things I’ve killed or else you’d realize that I’d have no problem shooting you right here. Where are all your demon pals anyway?”

Moriarty laughed. “Who cares? I don’t need them. Because I owe you, Sherlock. Only you.”

Dean gave an exasperated sigh and shoved Moriarty aside, which was quite easy for him to do. “I wouldn’t do that if I were you,” Moriarty sang.

“And why not?” Dean asked.

He didn’t get a response. Moriarty exchanged a glance with Sherlock who almost laughed. “How very original, really I expected better,” he said.

Moriarty shrugged. “It’s quick, it’s easy, and it’s effective.”

“What is? What are you talking about?” Sam asked.

“He’s rigged all of the doors with bombs. If they’re opened, the bombs go off, blowing up the building. He’s done this sort of thing before,” Sherlock said remembering the pool incident.

They all stood in silence for a few minutes until Dean looked over Moriarty’s shoulder and smiled. “Too bad you didn’t make the bombs angel proof.”

Moriarty got a puzzled look on his face and slowly turned around. When he did, Cas touched his forehead and he crumpled to the ground. Dean laughed and Sherlock laughed with him.

“I diffused the bombs and the building should now be demon proof. They will have a lot of cleaning up to do though,” Cas said looking around at the debris on the floor and the bit of blood on the walls.

“Sherlock! John!” They turned around to see Lestrade running towards them. His suit was disheveled and torn, his hair was a mess and he looked like he had just seen a ghost. Or an army of ghosts. They had momentarily forgotten about him.

“Goodness, are you okay?” John asked.

“I could ask the same thing,” Lestrade replied looking at the scarf around John’s shoulder which was almost soaked through with blood now and at his face which was bruised and had a streak of blood on it.

“I’m fine. We’re all fine.”

“Right. Good. Well I should help, um, get things in order here.” And with that he took a look at Sam, Dean, and Castiel and quickly turned and walked in the other direction.

“Come on you two, we should get out of here,” Dean said. When they got outside he patted Sherlock on the back. “Good job in there, man.”

Sherlock looked at him. “What? A demon was…inside of me,” he said for lack of a better choice of words.

“Yes but you were able to break through its shield in your mind, even if just for a second. Not many people can do that. He might be alive because of you,” he said glancing at John.

Sherlock was not entirely convinced but he was grateful for his words nonetheless. “Thank you.”

They made it back to Baker Street without either of them saying something sarcastic.


	11. Chapter 11

When they got back to Baker Street, John stitched up his shoulder with some help from Sam and Dean. Cas wanted to heal it himself but Dean insisted John learn how to clean and wound with whiskey, dental floss, and a needle.

“Might come in handy someday,” he insisted.

“So what are you guys going to do now?” John asked them after they bandaged up his shoulder.

“We’ll do one last sweep of the area, make sure they’ve moved on. We still haven’t caught Lilith so we’ll just have to track her down again. No biggie,” Dean said.

“What about the apocalypse thing?” Sherlock asked.

Dean chuckled. “Don’t worry, we got it covered. You guys are safe…oh wait.”

He pulled out two pentagram charms on chains, like necklaces. “You guys don’t seem like the tattoo type so we got you these. As long as you’re wearing them, demons can’t possess you.”

“What do you mean not the tattoo type?” Sherlock asked as he took the necklaces.

Dean and Sam pulled aside their shirts to reveal their tattoos on their chests. Sherlock raised his eyebrows. “I see…yes, we’ll take the necklaces.”

After an awkward pause Sam cleared his throat. “We better get going. People to see, demons to hunt.”

“Here’s our number,” Dean said handing a piece of paper to Sherlock. “If you ever need us, just call. Or pray to Cas, that’ll work too.”

“Don’t worry, London is safe with me,” Sherlock said but then he smiled. “But I’ll keep it in mind.”

Dean put out his hand and Sherlock shook it, Sam and Cas did the same. “You have one of the greatest human minds I have ever seen, don’t forget that,” Cas told him.

Sherlock looked surprised for a moment but then his face returned to normal. “I know.”

Sam, Dean and Cas shook hands with John next. “Thank you guys….for everything, especially saving Sherlock’s life. And mine too I suppose.”

Dean smiled. “Anytime. Like I said, just call.”

They said their final goodbyes and Cas put either of his hands on Sam and Dean’s shoulders and they vanished.

“They’re gone,” John said. “Just like that.” He laughed.

“Yes,” Sherlock replied. He sat down in his chair.

“Ok, what’s wrong with you?” John asked. “You’ve been acting off since we left Scotland Yard.”

“Nothing. I just…wanted to say sorry about that,” he said gesturing to John’s bandaged up shoulder.

John stared at him. “Sherlock that was not your fault at all so please don’t try to blame yourself or something.”

“I should have been able to overpower that demon much faster than I did,” he said with a growl.

“Sherlock, look at me,” John insisted. He did. “I don’t care what happened back there. I’m fine and you’re fine and that’s all that matters. I was so worried about you back there I didn’t even care what happened to me at first.”

“Don’t say that,” Sherlock snapped at him. “Don’t you say that. I could have killed you.”

“You didn’t.”

They looked at each other for a long moment and then John laughed. “You know, when I moved in with you I honestly can say I never expected this.”

“Really? You should learn to expect anything with me involved.”

They both laughed and just then there was a knock on the door. “Come in!” John yelled.

The door was practically thrown open and Mycroft stormed in, waving his phone in the air. “I just got off the phone with Lestrade. Would one or both of you care to explain?!”

Sherlock and John looked at each other and burst out laughing. “Sit down big brother, it’s a long story.”

**Notes for the Chapter:**

> Sorry the last chapter couldn't be shorter but there wasn't much more to it. I hope you've all enjoyed the story and as always, feedback is greatly appreciated! :)

**Author's Note:**

> Tell me your thoughts! :)


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